Concrete formulation

ABSTRACT

An additive for use in the preparation of lightweight concrete, said additive including a blend of from around 40% to 99% of organic polymeric material and from 1% to around 60% clean air entraining agent. The additive is particularly suitable for the preparation of lightweight concrete which uses polystyrene aggregate. It provides for excellent dispersion of the polystyrene aggregate and improved bond between the polystyrene aggregate and surrounding cementitious binder. The resultant lightweight concrete formulation may be pumped and is particularly suitable for sandwich wall construction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.09/958,614, filed Jul. 12, 2002, now U.S. Pat. No. 6,875,266, issuedApr. 5, 2005, the entirety of which is incorporated by reference, whichis the U.S. national phase of PCT Application No. PCT/AU00/00301, filedApr. 10, 2000, which designates the United States and which claimspriority to Australian application No. PP 9700, filed Apr. 9, 1999.

BACKGROUND OF THE INVENTION

The present invention relates to lightweight concretes and particularlybut not only to lightweight concretes for use as core infill forsandwich panel walling.

Field of the Invention

The technology involved in producing and pumping lightweight concrete iswell known in the prior art. It can generally be achieved using twotypes of density modifiers, namely foam and lightweight aggregate.

Foamed concrete is made by introducing a water-based, gas-filled foaminto a paste that is typically formed with water and Portland cementalone or Portland cement with a fine, lightweight aggregate. The foamstructure is developed by adding a gas-generating chemical to thePortland cement paste, or by mixing a pre-formed, water-based foam intothe cement paste to achieve a density below 1000 kg/m³.

The latter method requires that Portland cement be mixed with apre-formed aqueous foam that is produced using a commercial foamingagent, such as a hydrolysed protein. This approach requires a foamgenerator on site to make the foam.

Correct ratios of foam to concrete, particularly at the job site, aredifficult to maintain. This difficulty can lead to the possibility ofnon-uniformity of the final foamed concrete produced, as well asvariable mix quality, pumpability, extrudability, and finishingcharacteristics. The problems are exacerbated by the fact that the foambegins to collapse from the moment it is formed since the foam is notself-generating.

Lightweight aggregate concrete, made by mixing lightweight aggregatesuch as expanded polystyrene, perlite and vermiculite together with amortar is mainly targeted at applications with concrete density above1000 kg/m³. Difficulties arise, however, in mixing the cementitiousslurry and the lightweight aggregate due the tendency of the aggregateto clog and segregate because of its inherent composition and lowspecific gravity.

To make such polystyrene concrete pumpable, it may be necessary toincrease the water content in the mix to overcome friction in the pipes.This tends to aggravate the segregation and clogging problems associatedwith lightweight aggregate concrete production.

Such lightweight concretes ie. foamed concrete and lightweight aggregateconcrete have been used as core infill for sandwich panel walling butare subject to certain difficulties.

Foamed concrete exhibits a high hydrostatic pressure during core fillingwhich sometimes necessitates the use of structural formwork bracingduring core-filling of sandwich walls. The mix may also collapse heavilyduring pumping and pouring from the top of the wall height down into thewall cavity.

As far as lightweight aggregate concrete is concerned, core infill needsto exhibit a density of 1000 kg/m³ or below, which is outside the normaldensity range for lightweight aggregate concrete. To achieve this, up to1 m³ of bulk lightweight aggregate volume per 1 m³ of mix is needed tobe incorporated in the mix. This leads to difficulties in thecoatability of lightweight aggregates due to the insufficient mortarvolume present which consequently results in poor mix homogeneity andinsufficient bond between the mix constituents.

The inclusion of air-entraining agents (AEAs) to improve freeze/thawdurability, aid pumpability, improve workability, and lower the densityof concrete has long been practiced in the art. The AEA dose wasnormally specified to range between 5% to 9% air volume in the mix, withair content limit set to a maximum of 22% by ASTM C-150. Air contentshigher than this were normally avoided, especially in pumped concrete,for a range of reasons including:

during pumping a highly air-entrained concrete, the air bubbles tend tobreak upon impact with the pipe walls, joints elbows, forms, and thelike which leads to variable air contents in the placed concrete;

the pumping stroke can be absorbed by the compressible air enclosed bythe pipeline, leading to pumping failure;

the compressibility of excessive air during pumping will reduce itseffectiveness as a workable medium and make it more difficult to place;

excessive air in the mix can cause the placed wet concrete to collapsedue to the instability of the air-void system; and

highly air entrained concrete can lead to excessive reduction in thestrength of the hardened product.

It is an object of the present invention to overcome or ameliorate oneor more of the disadvantages of the prior art, or at least to provide acommercially useful alternative.

SUMMARY OF THE INVENTION

Accordingly, in a first aspect, the invention provides an additive forpreparing lightweight concrete, said additive including a blend ofaround 40 to 99% of organic polymeric material and from 1 to around 60%of an air entraining agent.

In another aspect, the invention comprises a lightweight concreteformulation including one part of cementitious binder, 0.5 to around 1.5parts by volume of inert filler, 2 to around 6 parts by volume oflightweight aggregate per part by volume of cementitious binder and upto around 2% by weight of the additive.

The additive allows the production of lightweight concrete mixcontaining preferably up to around 60% entrained air volume. Ideally,the concrete mix contains between 25% and around 50% entrained airvolume. This ultra high content is not normally used in concrete mixesdue to the difficulty in controlling the mix. Such a high airentrainment level normally also provides difficulties in workability,consistency in density and tendency to collapse, particularly if pumpedvertically or at high pressures.

The concrete produced from the abovementioned cement formulation, mayrange in density up to 1200 kg/m³, however, the improved air stabilityprovided by the blend additive allows the production of a lightweightconcrete with a density well below 1000 kg/m³ eg. 450-650 kg/rM³ withless lightweight aggregate volume than in conventional mixes ofcomparable density. By way of comparison, in one embodiment the use ofthe blend additive has allowed the polystyrene bulk volume in a 1 m³ ofmix to be reduced from around 1 m³ to around 0.7 to 0.8 m³. Thisreduction also results in better coatability of the polystyreneaggregate (i.e. helps ensure that the entire surface of each bead iscovered), improved mix workability, and improved bond between thelightweight mortar component and the polystyrene component in the mix.

In one preferred form of the invention the lightweight concrete producedby using the blend additive may be used as core infill in sandwichwalling applications without the need for internal or externalvibration, or formwork bracing. It also enables the use of nail-fixingof fibre reinforced cement facing sheet onto the steel framing memberswithout excessive bowing or blow out.

Preferably, the proportion of organic polymeric material in the additiveis between 60 and around 90% and more preferably between 70 and around85%.

Preferably there is between 10 and around 50% of the air-entrainingagent in the blend and more preferably between 20 and around 40%.

A broad range of organic polymeric materials may be used in the blend.Preferably the organic polymer will comprise one or more thixotropicagents which either dissolve in water or which at least form colloidaldispersions in the presence of water to produce an increase inviscosity. Suitable organic polymeric materials include cellulosederivatives such as hydroxymethylcellulose, hydroxyethyl cellulose orhydroxy propyl methyl cellulose; polysaccharides such as starches oralginate; and synthetic hydrophilic polymers and copolymers such aspolyvinyl alcohol, polyethylene oxide or polypropylene oxide.

Any suitable air entraining agents may be used. The term air entrainingagent refers to surface active agents (surfactants) which act to entrainair in the composition as it is mixed with water and/or pumped. Suitableair entraining agents include one or more nonionic, cationic and anionicsurfactants such as sodium salts of alpha olefin sulphonates and sodiumlauryl sulphate or sulphonate.

The additive may be mixed with a broad range of cementitious binderswhich include all inorganic materials comprising compounds of calcium,aluminium, silicon, oxygen and/or sulphur which exhibit hydraulicactivity ie. set solid and hard in the presence of water. Well knowncements of this type include common Portland cements, fast setting orextra fast setting, sulphate resisting cements, modified cements,alumina cements, high alumina cements, calcium aluminate cements andcements which contain secondary components such as fly ash, pozzolanaand the like. The term “cementitious binder” includes other well knownbinders such as fly ash, slag etc. and mixtures thereof with Portlandcement.

Suitable lightweight aggregates are also well known in the art. Theyinclude a range of natural and synthetic lightweight aggregates such asperlite, vermiculite and expanded polystyrene. The expanded polystyrenemay be in the form of balls, beads, pellets or reclaimed particles.

The lightweight concrete may also include between 50 and 100% by weightof the cementitious binder of an inert densifying ingredient inparticulate form or an inert particulate material. The term “inertparticulate material” indicates a material being inert with regard toother components of the composition, having a density greater than thelightweight aggregate and less than 5 mm in size. The preferred inertparticulate material is natural masonry sand.

In a further aspect, the present invention provides a method ofconstructing a wall comprising the steps of providing a frame having aplurality of substantially parallel mutually spaced apart frame members,attaching facing sheets to said frame and filling the cavity formedbetween said facing sheets with a lightweight concrete, the lightweightconcrete comprising a cementitious binder, a lightweight aggregate andup to 2% of an additive comprising a blend of 40-99% of organicpolymeric material or combination thereof and 1-60% of air entrainingagents.

In still a further aspect, the present invention provides a method forforming a pumpable lightweight concrete mix comprising the stops offirstly mixing the additive with water to form an aqueous solution,secondly adding expanded polystyrene aggregate to the aqueous solutionand thereafter adding cementitious binder.

Further unexpected benefits arise particularly when polystyrene is usedas a lightweight aggregate filler material. There is a known problemwith polystyrene in this context, in that the individual particles tendto develop electrostatic surface charges. This causes the aggregates toclump together and float to the top of the mix in situ, giving rise touneven distribution, compromised structural integrity, and largelynegating the intended effect. In order to overcome this problem, it isusually necessary to pretreat the polystyrene aggregates in order toneutralise them. This requires additional chemicals, a separate processstep, and often a subsequent drying process as well. However, theapplicant has found that by use of the above defined additive, thisproblem of clumping can be avoided. In this regard, the additive isinitially mixed with water to form an aqueous solution, and thepolystyrene is then added to this solution. Unexpectedly, this has beenfound to neutralise the surface charge on the polystyrene, without anyadditional chemicals or process steps being required. The solidcomponents are then added to the mix as a final step. By obviating theneed for a separate pretreatment process for the polystyrene aggregates,substantial material cost savings and production efficiencies can berealised.

Another advantage arising from the present invention when used inconjunction with polystyrene lightweight aggregate is the bond strengthbetween the polystyrene and concrete. For reasons that are not entirelyunderstood, the polystyrene does not normally bond well with acementitious binder. It is suspected that this may be due to thehydrophobic nature of the polystyrene aggregate. Not wishing to be boundby any particular theory, the applicant has found that use of theadditive defined above also increases the bond strength between thepolystyrene aggregate and the surrounding cementitious binder. This maybe due to the polystyrene aggregate being rendered hydrophilic or othermechanisms which cannot at this time be fully analysed. In any event, aswill be discussed below there is a substantial improvement in the bondstrength between the polystyrene lightweight aggregate and surroundingcementitious material.

Unless the context clearly requires otherwise, throughout thedescription and the claim, the words ‘comprise’, ‘comprising’, and thelike are to be construed in an inclusive as opposed to an exclusive orexhaustive sense; that is to say, in the sense of “including, but notlimited to”.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphic illustration of the dynamic response of conventionalmix-1100 kg/m³ density; and

FIG. 2 is a graphic illustration of the dynamic response ofair-entrained mix-500 kg/m³ density.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

So that the present invention may be more clearly understood it will nowbe described with reference to the followng examples.

Example 1-3 describes various mixtures of lightweight concrete usingpolystyrene aggregate, perlite and vermiculite as lightweight aggregateand sand and fly ash as fillers.

EXAMPLE 1 Use of EPS as Lightweight Aggregate and Sand as Filler

Mix Ingredients Quantity Unit Cement 50 kg Sand 40 kg PolystyreneAggregate 200 litres (50% solid/bulk ratio) Water 35 litres Blend: AirEntrainer (Anionic 0.1% by wt. of cement Surfactant) Organic polymer0.3% by wt. of cement Density of fresh mix 500 kg/m³ Yield of fresh mix250 litres % Entrained Air  30%

EXAMPLE 2 Use of Polystyrene as Lightweight Aggregate and Fly Ash+Sandas Filler

Mix Ingredients Quantity Unit Cement 30 kg Sand 20 kg Fly Ash 45 kgPolystyrene Aggregate 225 litres (50% solid/bulk ratio) Water 45 litresBlend: Air Entrainer (Anionic 0.1% by wt. of cement Surfactant) Organicpolymer 0.3% by wt. of cement Density of fresh mix 500 kg/m³ Yield offresh mix 280 litres % Entrained Air  30%

EXAMPLE 3 Use of Perlite as Lightweight Aggregate

Mix Ingredients Quantity Unit Cement 40 kg Sand 40 kg Perlite 40 litres(50% solid/bulk ratio) Water 30 litres Blend Air Entrainer (Anionic 0.3%by weight of cement Surfactant) Organic polymer 0.3% by weight of cementDensity of fresh mix 700  kg/m³ Yield of fresh mix 160  litres %Entrained Air  50%Comments on Examples 1-3

The mixes prepared according to those recipes were pumped into thecavities of a number of fibre reinforced cement lined sandwich walls,2400 mm.times.2400 mm.times.75 mm in size. Upon observation, it wasfound that the mixes were:

-   -   Pumpable, i.e. no clogging of line or segregation of mix was        observed.    -   Stable, i.e. the air-entrained mix sustained its level in the        wall cavity and did not collapse.

The YEELD of the fresh mix means the volume of the mix produced in onebatch. It is important that this yield is maintained after pumping andplacing of the concrete, which indicates the stability of the mix.

The density of the FRESH mix means the density of the concrete beforesetting, which is the one most critical to the application of wall corefilling.

EXAMPLES 1 and 2

Air Entrainer sodium lauryl sulphate Organic Polymer hydroxypropylmethylcellulose

EXAMPLE 3

Air Entrainer Myristamine Oxide Organic Polymer hydroxypropylmethylcellulose

The applicant has found that when the blend additive is used to producea lightweight aggregate concrete, the resultant mix has similarpumpability performance to that of a conventional lightweight aggregatemix.

Example 4 below compares the pumpability performance of two lightweightconcrete mixes, one with air entrainment and one without, containing asimilar volume of polystyrene aggregate. Sixteen batches of each mixwere produced, pumped to the 8th floor and used for core-filling ofsandwich walls lined with FRC facing. The two mixes were runback-to-back to minimise site, equipment and human interference with thecore filling rates produced. It can be seen that the core filling ratescorresponding to each mix taken as core-filled area (m2) divided bypumping time (hrs), were comparable.

EXAMPLE 4 Pumpability Performance of Lightweight Aggregate (Polystyrene)Concrete with and without Air-Entrainment

Non Air-entrained Air-entrained Mix Ingredients Conventional Mix Mix MIXDESIGN Cement 50 kg 50 kg Sand 90 kg 45 kg Polystyrene Aggregate 150litres 200 litres Water 37 litres 35 litres Blend nil 0.1% by wt. AirEntrainer (Anionic Surfactant) of cement Organic polymer (Celluloseether) nil 0.3% by wt. of cement % Entrained Air (calculated from yield 2% 25% and density measurements) % Polystyrene aggregate (calculated47% 47% from yield and density measurements) AT MIXING STATION Densityof fresh mix 1075 kg/m³ 525 kg/m³ Yield of fresh mix 170 litres 240litres Mixing/pumping time (16 batches) 100 minutes 75 minutes ON THE8^(TH) FLOOR Density of fresh mix 1100 kg/m³ 575 kg/m³ Loss in yield  2% 9% Wall core-filling rate 28.8 m²/hr 26.4 m²/hr

Clearly better mix pumpability resulted from inclusion of the blendadditive in the mix which led to reduced friction in the pipes. Also,less clogging of the pipes will be experienced due to improved mixhomogeneity, better coatability of beads and its segregation-freecharacteristic.

The applicants have found that the lightweight aggregate concreteresulting from use of the blend additive provides not only substantiallylower density but enables reduced hydrostatic pressure and dynamicthrust during core filling.

EXAMPLE 5 Extent of Bowing Comparison in Core-filled Walls

The two mixes shown in example 4 were pumped into a 400 mm wide, 2.4 mhigh wall cavity and the central deflection (bowing) on the 6 mm fibrereinforced cement (FRC) facing sheet during the core filling wasmeasured using Linear Voltage Displacement Transducers (LVDTs). They areshown in the table below: Deflection at 300 mm Deflection at 600 mmLightweight Concrete Mix from wall base from wall base Conventional 1000kg/m³ mix 4.00 mm 3.8 mm Air-entrained 500 kg/m³ mix  1.7 mm 1.6 mm

From the deflection measurements outlined above it can be seen that theair-entrained 500 kg/mr³ density mix enables around a 50% reduction inthe bowing of FRC facing when used as core infill in lieu of theconventional 1000 kg/m³ density mix.

EXAMPLE 6 Dynamic Thrust Comparison in Core-filled Walls

The two mixes shown in example 4 were pumped into a 400 mm wide, 2.4 mhigh wall cavity, and the dynamic response (thrust) during core fillingwas measured using an accelerometer mounted near the wall base. Theresults are shown in FIGS. 1 and 2. It can be seen that the lightweightconcrete (air-entrained) mix exhibited significantly less dynamic thrustcompared with the conventional polystyrene aggregate nor-air-entrainedmix.

The reduced hydrostatic pressure exemplified in example 6 hassignificant advantages over the prior art. It enables elimination of theneed for external formwork bracing to control bowing and blow-out of thewall panel. It also enables quicker construction since a nail gun may beused to fix the fibre reinforced cement facing sheets to the framerather than screw fixing. Reduced hydrostatic pressure and dynamicthrust during core filling also enables the use of lighter gauge steelframing due to less stiffness/torsional requirements.

A number of other surprising and unexpected benefits have been found toflow from the present invention including improved homogeneity of theresultant lightweight aggregate concrete. The lightweight mix is freeflowing, self levelling, segregation free and can be used to fill, forexample, the cavity in a sandwich wall without the need to consolidatethe mix by internal vibration or external tapping.

EXAMPLE 7 Moisture Retention Comparison

The two mixes shown in example 4 were poured into 2400 mm.times. 1200mm.times.75 mm walls constructed using studs of the same gauge at thesame pitch and allowed to cure at ambient conditions for two weeks. Thewalls were then transferred to a drying cell where they were subjectedto 20 cycles of 360 minute duration with half the time at ambienttemperature and the other half at 45.degree. C. This was followed with afurther 10 cycles of 60 minutes of heating at 70.degree. C. and 10minutes at ambient temperature. After the drying exposure, core sampleswere taken and the moisture content of each wall was determined at asimilar location in each wall.

The results of the moisture analysis revealed that the lightweightconcrete (air-entrained) mix retained 9.38% moisture compared to 5.13%moisture in the conventional polystyrene aggregate non-air entrainedmix. This indicates that, even after severe prolonged drying, thelightweight mix according to this invention exhibits water retentioncapability up to almost double the moisture retained in the conventionalmix.

From the above, it can be seen that the lightweight concrete mixexhibits superior water retention capability compared with conventionallightweight (polystyrene) concrete. This limits the volume of waterliberated by the mix within the wall cavity, resulting in reducedwetting of the fibre reinforced cement facing sheets. Consequently, thefacing sheets suffer less degradation in their structural properties. Inparticular, their stiffness and screw holding capacity are maintained,leading to less bowing and blow-out during core filling. Also, driersheets lead to lessened and more progressive shrinkage of the sheet asthe wall dries. This causes less strain (less opening) at the jointedgaps between the sheets.

Another outcome of the effect of improved water retention of the coremix is the reduced joint degradation due to the reduced volume of excessfree water coming from the mix and diffusing through the joints. Thisenables better adhesion of the base compound and less damage to anddistortion of paper jointing tape extending between adjacent facingsheets. Also, drier joints enable quicker and earlier jointing of wallson site and reduced degradation from any alkali dissolved in the cementwater permeating into the jointing zone.

EXAMPLE 8 Bond Strength Comparison

The walls subjected to drying in example 7 were tested for bond strengthbetween the fibre reinforced cement facing sheets and the two mixesoutlined in example 4. This was achieved by applying a tensile force tothe FRC/core interface at different wall levels along its height. Theresults are shown in the table below: Test location Bond Stress (MPa)along Conventional Failure Air-entrained Failure wall height 1100 kg/m³mix Mode 500 kg/m³ mix Mode  300 mm 0.12 Adhesive 0.14 Cohesive  900 mm0.07 Adhesive 0.11 Cohesive 1800 mm 0.08 Adhesive 0.08 Cohesive 2100 mm0.00 Adhesive 0.06 Cohesive

It can be seen that, upon cyclic drying, the air-entrained mix exhibitedless degradation in bond strength compared with the conventionallightweight mix. It can also be noted that the two mixes exhibiteddistinctly different failure modes. The conventional mix failed in an“adhesive” manner, i.e. by separation of the FRC component from the corealong their interface. The air-entrained mix, on the other band, failedin a “cohesive” manner, i.e. the FPC/core interface remained bonded andthe failure occurred in the core.

From the above, it can be seen that the lightweight mix according to thepresent invention exhibits superior adhesion to the fibre reinforcedfacing sheets. That is to say, the composite strength ofsheet/concrete/sheet is improved which leads to improvement in theoverall performance characteristics of the sandwich wall. This is quitesurprising since there was nothing to suspect that the additive orprocess for producing the lightweight concrete formulation would exhibitsuch superior adhesion. It will be clear to persons skilled in the artthat such “cohesive” failure is a substantial improvement over and aboveconventional techniques.

EXAMPLE 9 Anchor Pull Out Comparison

The walls subjected to drying in example 7 were tested for their anchorpull out load capacities. Anchor holes were drilled and two types ofanchors were inserted in both walls and tested by applying an axial loadto the bolt head until a peak load was reached defining anchor yielding.The results are shown in the table below: Pull out Load (KN)Conventional Air-entrained Anchor Type 1100 kg/m³ mix 500 kg/m³ mixHILTI HGN 12 (Ø10 mm Bolt size) 2.11 0.71 HILTI HHD 6/19 (Ø6 mm Boltsize) 0.90 1.30

It can be seen that when an anchor intended for conventional lightweightconcrete was used, i.e. the HILTI HGN 12, the air-entrained mixexhibited 65% lower pull out load compared with the conventional mix.Since this anchor relies on core density to achieve its pull out loadcharacteristic, the fact that the lightweight concrete is 55% lower indensity translates into reduced tensile strength and consequentlyreduced pull out strength.

On the other hand, when a cavity wall anchor HILTI HHD 6/19 was used,the table shows that the pull out force trend relating to the two mixeswas reversed, i.e. the air-entrained mix exhibited 44% higher pull outload compared with conventional mix. This result is believed to berelated to the improved bond strength of the air-entrained mix whichhelps transfer the pull out forces directly to the facing sheet, due tothe presetting action required by the anchor prior to its being loaded.When the HHD type anchor is set, the body is collapsed into fourradially oriented arms that come into contact with the facing skin. Inshort, the carrying capacity/density ratio of the core mix issubstantially improved.

This result is quite surprising. Not only does the lightweight concreteprovide good insulation due to high entrained air volume, but at thesame time it meets acceptable hanging capacity requirements needed forhanging basins, cupboards, and the like.

EXAMPLE 10 Density Modification

Typical formulations for lightweight concrete with densities of 1200kg/m³ and 450 kg/m³ are shown. Both examples showed excellent dispersionand bond strength with the polystyrene aggregate. Mix Density 1200 1200Litres Kg Ratio by vol. Ratio by wt. Binder 253 354 100.00% 100.00%Inert Filler 394 630 155.56% 177.78% Poly Aggregate 295 3 116.67% 0.83%Water 211 211 83.46% 59.61% Additive 7 2 2.72% 0.68% Mix Density 450 450Litres Kg Ratio by vol. Ratio by wt. Binder 108 151 100.00% 100.00%Inert Filler 95 151 87.50% 100.00% Poly Aggregate 946 9 875.00% 6.25%Water 140 140 129.85% 92.75% Additive 6 2 5.25% 1.31%

In all these respects, the invention represents a practical andcommercially significant improvement over the prior art.

Although the invention has been described with reference to specificexamples it will be appreciated to those skilled in the art theinvention may be embodied in many other forms.

1. A polystyrene lightweight aggregate for use in the preparation oflightweight concrete, said aggregate being treated with a treatmentagent including a blend of around 40% to 99% of organic polymericmaterial and about 1% to 60% of an air entraining agent.
 2. An aggregateaccording to claim 1, wherein said treatment agent including betweenabout 10% and 50% of the air entraining agent.
 3. An aggregate accordingto claim 2, wherein said treatment agent including between about 20% and40% of the air entraining agent.
 4. An aggregate according to claim 1,wherein the organic polymeric material includes one or more thixotropicagents to enhance viscosity.
 5. An aggregate according to claim 1,wherein the organic polymeric material is a cellulose derivative, apolysaccharide, or a synthetic hydrophilic polymer.
 6. An aggregateaccording to claim 5, wherein the organic polymeric material is selectedfrom a the group consisting of hydroxymethylcellulose, hydroxyethylcellulose, hydroxy propyl methyl cellulose, starch, alginate, polyvinylalcohol, polyethylene oxide and polypropylene oxide.
 7. An aggregateaccording to claim 1, wherein the air entraining agent includes one ormore nonionic, cationic or anionic surfactants.
 8. An aggregateaccording to claim 7, wherein the air entraining agent is a sodium saltof alpha olefin sulphonate, or sodium lauryl sulphate or sulphonate. 9.An aggregate according to claim 1, wherein said treatment agentincluding between about 60% and 90% of the organic polymeric material.10. An aggregate according to claim 9, wherein said treatment agentincluding between about 70% and 85% of the organic polymeric material.